The origins and evolution of the modern Indo-Pacific reef algal flora: the coralline algae in the context of the THROUGHFLOW Project

South East (SE) Asia hosts the global centre of maximum diversity for shallow marine ecosystems, mainly associated with thriving coral reefs (Renema et al., 2008). The factors responsible for the origins and maintenance of this diverse biota remain unknown. Previous studies suggest that the formation of the ancestral centre of diversity could be related to the constriction of the Indonesian Throughflow current (ITF) during the Cenozoic, resulting in increased speciation and/or immigration during the Miocene. Unfortunately, the fossil evidence currently available to document this pattern and its geographic context is sparse, and there is a need to collect new data.

The scientific objective of the THROUGHFLOW Project is to reconstruct the biological and environmental history of shallow marine habitats of a selected area of Southeast Asia. Specifically, a multidisciplinary study of key sections in Eastern Kalimantan (Indonesia) will be performed, integrating data from geology, geochemistry, ocean modeling, and paleontology to understand the Neogene history of the region.

In this framework, the projects carried out at Granada University aim to document the timing and patterns of the diversification of Indo-Pacific reef-building coralline algae, the second most important builders in modern Indo-Pacific reefs. The collected data will be integrated with a robust sedimentological framework for detailed reconstructions of the shallow marine carbonate paleoenvironments and their evolution through time.

The first expedition has been already carried out in East Kalimantan (Indonesia) during November-December 2010. A variety of shallow marine ecosystems, including coral reefs and sea grass environments, were found. First results show an exceptional preservation of some fossil algae, especially in places with a high siliciclastic influence (Miocene deposits of the Mahakam Delta). A new expedition is scheduled for summer 2011. We will study a wider temporal (Early to Late Miocene and possibly Late Oligocene) and spatial range of outcrops.

Acknowledgements: This paper is a contribution to the project supported by Marie Curie Actions, Seventh Framework Programme (Grant No. 237922).